1. Field of the Invention
The present invention relates to a suction device for a hand-held tool having a plate-like working tool, and including a hood-shaped housing covering a rear side of the working tool and partially a working tool circumference and connectable with a device for creating vacuum, and a protective screen formed of a flexible material and extending along a circumference of a free end surface of the housing, projecting axially above the free end surface.
2. Description of the Prior Art
Dust, which is formed during treatment of the structural components with conventional hand-held tools, in particular with grinders, is aspirated from the work location by a suction device and is delivered to a collector. One of such hand-held tools formed as an angular grinder is disclosed in a French Publication No. 2,712,835. The suction device of this angular grinder has a hood-shaped housing which surrounds a circumferential region of the plate-like working tool of the angular grinder which tool is formed as a grinding wheel. The hood-shaped housing is secured to the housing of the angular grinder.
At a free, in the working direction, end of the suction device housing, there is provided a protective screen which projects above the housing free end and so seals the housing inner space from the surrounding environment that a vacuum can be created in the housing inner space by vacuum generating means. The protective screen is formed of a strip made of a flexible elastic material and bent into a ring. A certain air volume, which is aspirated by the vacuum generating device from the housing through an outlet opening, is aspirated from outside into the housing interior through a suction cross-section. The suction cross-section is formed by an intermediate space between the protective screen and the structural component, which intermediate space is formed when a non-worn grinding wheel abuts the structural component.
During treatment of the structural component, the grinding wheel wears off, and the protective screen contacts the structural component. This reduces the suction cross-section, and the protective screen becomes subjected to wear. The reduction of the suction cross-section results in increased vacuum in the housing interior, and the housing becomes attached to the structural component more and more. This results, in turn, in that the grinding wheel is pressed more strongly to the structural component which leads to a more rapid wear-off of the grinding wheel. As a result of this, the displacement of the grinding wheel over the structural component becomes more difficult, and the load on the drive motor of the grinder greatly increases.
Accordingly, an object of the present invention is to provide a suction device the protective screen of which is not subjected to wear, and an adequate size of the suction cross-section is insured.